On the clothes issue, did you actually have your own individual clothes - and if so, did you have a way of distinguishing whose were whose?
I'm thinking that, if you have two or three children of the same sex and who are a similar size, the temptation must be to just grab a suitable garment for whichever child as it comes, rather than being strict about who wears what.
Also other things, like bikes - did you have one each or just a 'selection' for the family and you took one that was a suitable size when you needed one?
Did you have a place on a sofa or an armchair for each of you? Thinking practically, you'd need a minimum of 4 3-seater sofas, which I think many living rooms - even in larger houses - would struggle to accommodate.
Part of what is making me wonder this is because I have (now very much grown up) cousins who had 'only' 4 children in the family, and they always had a caravan - it was almost 'iconic' as part of their family identity - but it was only a few years ago, when I spoke to one of them at a funeral, that I learned that the two older children always had to sleep in the awning... so although they had family caravanning holidays, for two of them, they were only essentially camping holidays.
This is probably a silly one, but did your parents have a naming theme for you all - e.g. all beginning with the same letter or Alice, Brian, Chloe ...; and are they all 'off the same shelf'? Did names get recycled - especially middle names?
Do you think they considered long and hard about every child's names - even though MN and the Baby Names forum wasn't around then - or just picked 'safe' or predictable ones... and was there a clear difference between the older kids' names and the younger ones' names, if they started to run out of 'favourite' names? I suppose a lot of this would depend on whether they planned how many they were wanting from the outset, which I'm guessing they probably didn't?